Treatment of petroleum cracking residues



July 6, 1948. E. HENE TREATMENT OF PETROLEUM CRACKING RESIDUES 2Sheets-Sheet 1 Filed Aug. 17, 1945 n 0 Q a Me eH m, W2 M 4v m 5% E. HENETREATMENT OF PETROLEUM CRACKING RESIDUES Jul 6, 194.

2 Sheets-Sheet 2 Filed Aug. 17, 1945 I jw u efi ior; 57m? Hem: y

Patented July 6, 1948 TREATMENT, OF PETROLEUM CRACKING RESIDUES EmilHene, London, England Application August 17, 1945, Serial No. 611,129 InGreat Britain August 31, 1944 Claims. (01. nae- 29) This inventionrelates to the treatment of petroleum cracking residues.

A number of processes are known to produce distillates and coke frompetroleum cracking residues (hereinafter referred to as residues) 1 byheating such residues on coke lumps.

A close examination of the behaviour of such residues showed that duringsuch heat treatment a variety of heavy asphalt-like hydrocarbons eitherpresent in the original residue or formed during the heat treatment coatthe coke lumps for a considerable time in the liquid phase before finalcoking can be achieved. During this period no fresh charge of residuecan be admitted as otherwise a pitchy mass would result making anymechanical or continuous operation impossible. The decomposition ofthese hydrocarbons was, therefore, considered necessary and it has beeneffected either by raising the temperature or by allowing sufficienttime for the decomposition to take place.

A number of experiments has shown that such decomposition of thesehydrocarbons occurs only very gradually \by releasing volatilehydrocarbons and leaving hydrocarbons with a lower ratio of hydrogen tocarbon, their colour becoming gradually darker, their softening pointshigher while at the same time their resistance to decompositionincreases constantly during their approach to coke. Therefore, if onlycoke and distillates are to be produced, the throughput is to a greatdegree dependent on the time required for the coking of these refractoryhydrocarbons.

Even when these hydrocarbons represent only of the weight of the charge,the time necessary for their decomposition will be several times greaterthan that necessary to reach that point.

It has now been found according to this invention to be possible toremove these hydrocarbons without their destruction and to recover themas such so that not only a very considerably increased throughput butalso, as the examination of these hydrocarbons showed, a convenientrecovery of very useful hydrocarbons can be achieved.

Accordingly, the present invention provides a process for themanufacture of hydrocarbon distillates, coke and asphaltic material fromresidues obtained in the cracking of petroleum which comprises soakinglumps of coke or like porous carrier with the residue, heating the samein a gaseous or vapo-rous atmosphere so as to evaporate the morevolatilehydrocarbons and leave a coating of the less volatile hydrocarbons andof coke, and submerging the thus coated lumps in a molten metal or saltat a temperature above the softening point of the hydrocarbons formingthe coating so as to cause liquid products to rise to the surface of themolten material. I

Instead of coke I may use a like forming carrier, for example woodcharcoal.

Preferably both steps are'carried out within the temperature range of400 C. to 550 C. Preferably a molten lead bath is used and the action ofthe molten metal or salt seems to be to squeeze out the liquidhydrocarbons which collect on the top thereof from whence the liquidhydrocarbons can easily be removed and recovered as such, while thesolid hydrocarbons stick to the surface of the lumps which after a shortperiod of heating are ready to receive a fresh charge of residue.

It will thus be seen that the process of the present invention enablesdistillates, asphalt-like fractions and coke to be obtained fromcracking residues in one operation with high throughput and heatefficiency.

Cracking residues useful for the process of the invention may beobtained by cracking hydrocarbons as they occur in natural or syntheticpetroleum, in asphalts, bituminous or waxy deposits and removing thelighter fractions. They may be blended with hydrocarbons from cracked oruncracked stocks.

Two embodiments of the invention will now be described in greater detailby way of example with reference to the accompanying drawings i which: ii

Fig. 1 is a front sectional View of one embodiment of this apparatuswith furnace removed.

Fig. 2 is an end sectional view corresponding to Fig. 1 but includingthe furnaces, and

Fig. 3 is a front sectional View of a second embodiment.

Referring to Figs. .1 and 2 of the drawings a perforated cylindricaliron drum l is rotatably mounted in a bath 2 containing molten lead 3heated by heating means 4 disposed in furnace l9 provided with flue 20,the axis of the drum being horizontally disposed. The level of the leadis below the axis of the drum and the drum is divided into sections bymeans of radially disposed perforated plates 5, and about two-thirds ofthe space within the drum is filled with lumps of coke 6. The pre-heatedcharge is introduced into the drum I through a pipe I at the top of thebath, the pipe leading to a horizontal manifold 3 with a plurality ofopenings 9. The vapours evolved escape througha pipe H1 at the top-ofthe bath and are condensed, and the liquid hydrocarbons displaced by themetal ibath escape through an overflow pipe H at the side of the bathslightly above the level of the molten metal. Fresh coke can be chargedfrom a hopper #2 by means of an axially disposed screw conveyor l3,while coke which has sufficiently increased in weight is removed bymeans of a further axially disposed screw conveyor l4 at the other endof the drum'to a hopper l5. Tubes 16 and i! may be provided throughwhich gas under pressure can be introduced into the conveyor housing, toprevent vapours entering the conveyors. A lead trap 18 may 'beconnectedwith the overflow for the liquid products. The l is supported inbearings 2| and 22 and is driven through pulley 23 and belt 29.

Referring to Fig. 3 of thedrawings the preheated charge of residue isfed through a pipe 25 on to hot coke lumps 26 floating on a bath ofmolten lead 21 contained in a cylindrical vessel 28 having a verticalaxis. 'The lead is heated by heating means 29 disposed in furnace 36having a flue- 3|. After the coke has soaked sufliciently in theresidue, a short time is allowed for evaporation of volatileconstituents. Then a perforated disc 32 fitting inside the cylinder ispushed down until all the coke is submerged in themolten lead, the leadcontent of the cylinder'being such that the lead rises up to an overflowpipe 33 so that the liquid hydrocarbons formed run into a container 34connected to the pipe. A lead trap 35 is provided in the pipe andretains any molten lead that might have been carried over. Vapoursproduced are removed through a pipe 35 near the top of the cylinder andcondensed.

The coke is charged from a. hopper 37 above the aforesaid vapour pipeand; the excess after treatment is removed by the aid of a plunger 33disposed in a sleeve 39 fitted at the side of the Cylinder.

The coke removed is received in a hopper til.

When the coke has been submerged for a sufiicie'nt time, the disc 32 ismoved up and a fresh charge of residue applied to the rising coke.

In both embodiments the area above the lead bath is well lagged orprovided with additional heating means.

The composition and proportion of the various fractions obtainable froma given charge can be varied.

(cl By varying the temperature f the lead bath; if the temperature isincreased the proportion of distillates increases as well as that ofthe, coke, but they may become darker if the pressure is not alsoincreased. The proportion of asphalt-like hydrocarbons decreases.

(b), By, the application of increased or reduced pressure; an increaseof pressure will lead to an? increase of the asphalt-like hydrocarbonsand of coke, the latter especially when the temperature is increased atthe same time.

"A' similar effect to that obtained by the use offreduced pressure canbe obtained by the use of carrier gas or vapours or the addition oflower boiling fractions to t'he charge.

By varying the period during which the c clumps are inside or outsidethe lead bath; crease of 'the'period during which the coke lumps areoutside "the bath will lead to a reduction of proportion oftheasphalt-like hydrocarb ns whi e t e' We. r ii as; at the s t n t he oftni g oin Qf the sn alt-li se liviiroearbonsjwi l. ani ine? compositionchange, as can easily be ascertained by solvent extraction.

The longer the period of submersion of the coke in the lead bath thelower becomes its volatility; a similar result is obtained by usinghigher temperatures.

It may be remarked that the composition of the residue is of greatimportance and the properties of the fractions can be modified veryconsiderably by varying the orginal cracking conditions or by blending.

.The following are the general properties of the three fractionsobtained, in addition to which a small proportion of gas (M -3%) is alsoobtained;

1. Distz'Zlates.-They range from hydrocarbons boiling atordinarytemperatures to resinous hydrocarbons, the proportions depending on thenatureof the residue and the conditions of the treatment. They may berecovered by fractional condensation, the heavier fractions being stocksfor lubricating oils and drying oils. A large variety of useful productscan be obtained from them with the aid of solvents.

The hydrocarbons in the gas oil range may be used as a fuel or forblending; thus a large proportion of residue can be converted into auseful fuel by treating a proportion according to the process andblending the suitable distillates with untreated residue.

2. Asphalt-like hydrocorbons.-They have the appearance of asphalt andmay be used for purposes for which asphalt is used, either as such orafter blending with suitable material. They can be obtained with a highsoftening point, making transport and storage easy. By solvent treatmentuseful hydrocarbons of resinous nature can be extracted.

A proportion can, for example, be extracted with petroleum ether. Thesehydrocarbons are resins of low softening point. They can be furtherseparated by treatment with furfural into various types, the part in thelower layer generally having drying properties or being lubricatingstock; but in some cases these products were found in the top layer andthe lower layer contained resins of somewhat higher softening points. Avariation of the proportions of furfural and the temperature of itsapplication will enable a variety of products to be produced and thedesired method of treatment to be found. However, other solvents may beemployed to obtain a different variety of products.

Generally, these hydrocarbons are easily emulsif able and compatiblewith nitrocellulose and, therefore, very useful for painting and coatingwhen used as such or in mixtures with other products. Drying oilsobtained by the process are miscible with linseed oil in all proportionswithout reducing the drying property of the mixture.

The same observations were made regarding the heavier fractions of thedistillate.

The residue from the petroleum ether extraction contains a proportion ofhydrocarbons soluble in benzole anda larger one soluble in solventnaphtha. These hydrocarbons are very often black, shiny, very resistantto acids, and they dry from their solution with a hard, glossy, blackThey are useful for incorporation in paints and lacquers. The softeningpoint of the dry resin is often about 7Q to C.

The residue from this extraction consists of hydrocarbons which are anintermediate stage the rqdu iqa i sake while those vi Present d furthe wr r ie ed s ol ds by absorption by the coke lumps. They are solid atordinary temperatures, but very soft and, for example, very useful aspigments as they are almost free from coke.

3. Cke.--The coke can be recovered as loose lumps which makes continuousand automatic operation very easy and increases its value for manypurposes.

It can be used as a fuel or for chemical reactions. If it is intendedfor use for making carbon disulphide, where normal coke (for example gascoke) is unsatisfactory, the original coke lumps may be wood charcoal orcrushed lumps from previous operations. If it is desired to obtain cokewith some inorganic matter fairly homogeneously distributed, such mattermay be mixed with the charge in powdered form. Organic matter (forexample sawdust) may be used in the same Way to increase porosity.

It may be remarked that the process of the invention can easily becontrolled by the softening point of the asphalt-like hydrocarbons orthe proportions of the various distillates during fractionalcondensation.

The term gaseous as used in the appended claims includes vaporous.

I claim:

1. A process for the manufacture of hydrocarbon distillates, coke andasphaltic material from residues obtained in the cracking of petroleumwhich comprises soaking lumps of porous carrier material with a residueobtained in the cracking of petroleum, heating the soaked lumps in agaseous atmosphere so as to evaporate the more volatile hydrocarbons andleave a coating of the less volatile hydrocarbons and of coke on thelumps of porous carrier, and submerging the thus coated lumps in amolten material selected from the group consisting of molten metals andmolten salts, at a temperature above the softening point of thehydrocarbons forming the coating so as to cause liquid products to riseto the surface of the molten material.

2. A process for the manufacture of hydrocarbon distillate coke andasphaltic material from residues obtained in the cracking of petroleumwhich comprises soaking lumps of coke with a residue obtained in thecracking of petroleum, heating the soaked lumps in a gaseous atmosphereso as to evaporate the more volatile hydrocarbons and leave a coating ofthe less volatile hydrocarbons and of coke on the lumps of porouscarrier, and submerging the thus coated lumps in a molten materialselected from the group consisting of molten metals and. molten salts,at a temperature above the softening point of the hydrocarbons formingthe coating so as to cause liquid products to rise to the surface of themolten material.

3. A process for the manufacture of hydrocarbon distillates, coke andasphaltic material from residues obtained in the cracking of petroleumwhich comprises soaking lumps of coke with a residue obtained in thecracking of petroleum, heating the soaked lumps in a gaseous atmosphereat a temperature of between 400 and 550 C. so as to evaporate the morevolatile hydrocarbons and leave a coating of the less volatilehydrocarbons and of coke on the lumps of porous carrier, and submergingthe thus coated lumps at a temperature of between 400 and 550 C. in amolten material selected from the group consisting of molten metals andmolten salts so as to cause liquid products to rise to the surface ofthe molten material.

4. A process for the manufacture of hydrocarbon distillates, coke andasphaltic material from residues obtained in the cracking of petroleumwhich comprises soaking lumps of porous carrier material with a residueobtained in the cracking of petroleum, heating the soaked lumps in agaseous atmosphere so as to evaporate the more volatile hydrocarbons andleave a coacting of the less volatile hydrocarbons and of coke on thelumps of porous carrier, and submerging the thus coated lumps in moltenlead at a temperature above the softening point of the hydrocarbonsforming the coating so as to cause liquid products to rise to thesurface of the molten lead.

5. A process for the manufacture of hydrocarbon distillates, coke andasphaltic material from residues obtained in the cracking of petroleumwhich comprises soaking lumps of coke with a residue obtained in thecracking of petroleum, heating the soaked lumps in a gaseous atmosphereat a temperature of between 400 and 550 C. so as to evaporate the morevolatile hydrocarbons and leave a coating of the less volatilehydrocarbons and of coke on the lumps of porous carrier, and submergingthe thus coated lumps at a temperature of between 400 and 550 C. inmolten lead so as to cause liquid products to rise to the surface of themolten lead.

EMIL HENE.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS

